1. Technical Field
This invention relates to devices used to determine relative angles from a predetermined point.
2. Description of the Prior Art
Prior art devices of this type have relied on a variety of different structural configurations. See for example U.S. Pat. Nos. 1,139,648, 1,086,545, 843,459 and 3,065,546.
In U.S. Pat. No. 1,139,648, a combination tool is disclosed having a fixed right angular square with a large circular opening at the base with a disc-like portion so the same will revolve showing the relative angle.
In U.S. Pat. No. 1,086,545, a ruler is shown having a ring defining a protractor hinged from which extends two ruler elements.
U.S. Pat. No. 843,459 defines a combination ruler and square in which two main members are pivoted together at one end with a locking screw therebetween.
U.S. Pat. No. 3,065,546 discloses an extension ruler having an elongated center portion which is pivoted at one end being movable outwardly from the ruler with a track member therebetween indicating the relative degrees between the two extensions.